Which molecule is a double-stranded helix consisting of deoxyribose, the bases A, T, C, G, and is capable of being replicated?

• A. Ribonucleic acid
• B. Nucleic acid
• C. Deoxyribonucleic acid
• D. Protein

Answer: (C)

The concept being tested is recognizing DNA by its defining features: a double-stranded helix made with a deoxyribose sugar and bases A, T, C, G, and the ability to be copied during replication. Deoxyribonucleic acid fits all of these traits: it is the genetic material that can be replicated to pass genetic information to new cells and offspring. Its sugar is deoxyribose, and its bases pair specifically as A with T and C with G within the double helix. In contrast, ribonucleic acid uses ribose and typically is single-stranded, often contains uracil instead of thymine; the broad term nucleic acid covers both DNA and RNA; and proteins are not nucleic acids and do not have this sugar-base structure.